Certain connectors for coaxial cable which are commercially available, include a coupling nut assembled to the outer conductive shell which threadedly couples with the outer conductive shell of a mating connector to bring together and retain the connectors in an assuredly mated condition to interconnect a coaxial cable to another like cable or to an electrical apparatus or the like. The connector includes an inner contact or inner conductor within a dielectric sleeve all within the outer conductive shell. The inner contact is electrically engageable with a contact terminated onto the signal conductor of the coaxial cable, which is disposed within an insulative jacket, all within an outer cable conductor. Certain coaxial cable has a semirigid outer conductor such as of copper alloy, and the outer conductive shell of the connector is commonly soldered to the semirigid conductor; the center conductor of the cable includes an end section extending forwardly from the cable end and is commonly received into and mated with a rearward socket section of the inner contact of the connector. The coupling nut is secured to the outer conductive shell in a manner permitting rotation thereabout but is stopped from axial movement therealong; the coupling nut is rotated about the first connector to become fully threaded to the mating connector, incrementally drawing the mating connector toward the first connector and its mating face firmly against the mating face of the first connector for the complementary inner and outer conductors to become electrically connected.
One particular such coaxial connector is disclosed in U.S. Pat. No. 5,232,377. A retention sleeve is disclosed therein to be placed on the outer conductive shell and includes a forward end which defines the rearward stop for coupling nut retention. The retention sleeve includes an inner diameter which is incrementally smaller than the outer diameter of the rearward section of the outer conductive shell to establish an interference fit with at least a portion of the rearward section. The retention sleeve further includes an inwardly directed annular flange at the rearward end thereof which abuts the end of the rearward shell section for controllably locating the fully assembled position of the retention sleeve on the outer conductive shell.
In the connector of U.S. Pat. No. 5,232,377, the bore of the rearward section of the outer conductive shell includes a larger diameter rearward bore portion providing a seat for placement of an annular solder preform or ring thereinto prior to placement of the retention sleeve onto the outer conductive shell. Preferably the periphery of the apertures through the inwardly directed annular flange of the rearward end of the retention sleeve is chamfered to form a lead-in to facilitate insertion therethrough of the end of the semirigid coaxial cable.
Further, the retention sleeve is composed of low resistance non-magnetic metal; the outwardly facing surface of the retention sleeve includes a thin layer of high resistance magnetic material integrally joined thereonto. So fabricated, the retention sleeve defines a Curie point heater of the type disclosed in U.S. Pat. No. 4,852,252. Such a heater is a self-regulating temperature thermal energy source achieving a temperature sufficient to reflow solder when subjected to radiofrequency current, in the manner as is generally disclosed in U.S. Pat. Nos. 4,256,945 and 4,659,912. For cable termination, the connector assembly containing the solder preform therewithin receives the end of the semirigid cable into the rearward section thereof, which electrically engages the inner contact with the signal contact of the cable, and is then subjected to high frequency alternating current such as radiofrequency current (RF) of 13.56 megaHertz for several seconds. The self-regulating temperature heater defined by the retention sleeve generates thermal energy until a Curie point temperature is achieved such as about 240.degree. C., a certain amount higher than the reflow temperature such as about 183.degree. C. The thermal energy reflows the solder of the preform which flows along the surface of the semirigid cable and the inwardly directed annular flange of the retention sleeve to form a solder joint between the cable's outer conductor and the retention sleeve which is assuredly electrically joined to the outer conductive shell of the connector by the interference fit.
It is desired to obtain an assured solder joint of the semirigid cable outer conductor to a coaxial connector having a retention sleeve of the type containing solder therewithin.